This invention relates to wet and dry strength additives for use with paper and particularly to additives derived from the condensation of an aromatic polymer having a plurality of pendant amine groups, with an epihalohydrin.
As is well known, untreated paper, when wet, becomes exceedingly soft and tends to fall apart as the fibers of the paper lose interfiber bonding. To combat this tendency it has been found expedient to add to the paper a polymer that will adhere to the fibers and bond them together at the points where the fibers are in contact. The polymers help the paper to maintain its structure even when wet and are said therefore, to confer "wet strength".
There are a number of polymers that have been employed for this purpose but probably the most successful have been those produced by the reaction of a polyamine with an epihalohydrin. This invention falls into this category but represents an advance in the art in terms of its superior hydrolytic stability, high polymer yield, efficiency of usage of the relatively expensive epihalohydrin and amine monomer reactants and very fast cure to produce the strengthened paper.